This invention relates to overhead doors and, more particularly, to overhead sectional door panels having sheet like skins and the associated method of manufacturing such systems.
There are numerous designs of overhead or retractable door assemblies which are commonly used for garage doors, truck doors, warehouse doors or the like. Typically, an overhead door of this type is convertible between an open, overhead or generally horizontal configuration and a closed generally vertically oriented configuration in which the door closes an opening in the building or the like. The overhead door is typically movable along a track assembly mounted proximate the opening and the track assembly commonly includes a generally vertical track section, a generally horizontal track section and a curved transition track section joining the horizontal and vertical sections together.
Retractable overhead doors of this type are conventionally constructed of a number of vertically arranged, horizontally oriented panels which can fold along the horizontal divisions between the panels to enable the door to pass along the curved transition section of the track when being opened or closed. The panels can be pivotally coupled together with hinges on the interior surface or back face of the door panels. The hinges articulate during pivotal movement of the panels. Such door panels for many years were predominantly constructed of wood. However, wood door panels are both costly to manufacture and heavy in use, resulting in difficulty when opening and closing the garage door.
Recently, sectional overhead door panels having an outer metal skin have become popular and have replaced wooden door panels in many applications. Commonly, sectional overhead door panels which are rolled or formed by thin sheet metal require internal reinforcing members, typically constructed of wood or metal. Center and end stiles are often provided within the sheet metal door panel for the required reinforcement.
However, in many instances to obtain a lightweight panel with the requisite strength and rigidity, the sheet metal skin thickness must be increased. This increased skin thickness can add significant material and production costs to the door panel. In many applications, the added strength resulting from the increased skin thickness is required. However, it is well recognized that no single overhead door panel design satisfies the needs of all applications and installations. In addition to skin thickness and strength, a wide range of other panel characteristics may be altered for the appropriate panel design for a given application. However, in known overhead door systems, a change in one panel characteristic typically requires an entire different door panel, skin and/or associated components and production scheme. Such changes are inefficient from both a cost and production schedule standpoint.
Another aspect of known overhead sectional doors is the use of an astragal strip mounted along the bottom edge of the lowermost panel to seal the door against the floor. However, since the door panels are typically manufactured as identical components, mounting hardware is required to install the astragal to the lowermost panel of the overhead door. Such added mounting hardware often adds weight to the door, increases both the inventory of components and the cost of installation of the door.
As evidenced by the above background, a need exists for overhead door panel which provides the required performance characteristics including, among others, strength and rigidity to withstand the wind and structural loads associated with many overhead door applications while remaining lightweight. Furthermore, the door panel must be efficiently, easily and economically manufactured with a minimum of component parts while providing the desired physical attributes.